refactor(fs): reduce overhead of watch (tauri-apps#2613)

Author: Legend-Master

.changes/fs-watch-cleanup.md

@@ -0,0 +1,6 @@
+---
+fs: minor
+fs-js: minor
+---
+
+Reduce the overhead of `watch` and `unwatch`

Cargo.lock

@@ -69,6 +69,7 @@
     "fs:allow-mkdir",
     "fs:allow-remove",
     "fs:allow-write-text-file",
+    "fs:read-meta",
     "fs:scope-download-recursive",
     "fs:scope-resource-recursive",
     {

examples/api/src-tauri/capabilities/base.json

@@ -2,16 +2,18 @@
   import * as fs from "@tauri-apps/plugin-fs";
   import { convertFileSrc } from "@tauri-apps/api/core";
   import { arrayBufferToBase64 } from "../lib/utils";
+  import { onDestroy } from "svelte";
 
   export let onMessage;
   export let insecureRenderHtml;
 
   let path = "";
   let img;
+  /** @type {fs.FileHandle} */
   let file;
   let renameTo;
   let watchPath = "";
-  let watchDebounceDelay = 0;
+  let watchDebounceDelay = "0";
   let watchRecursive = false;
   let unwatchFn;
   let unwatchPath = "";
@@ -118,7 +120,7 @@
                     .getElementById("file-save")
                     .addEventListener("click", function () {
                       fs.writeTextFile(path, fileInput.value, {
-                        dir: getDir(),
+                        baseDir: getDir(),
                       }).catch(onMessage);
                     });
                 });
@@ -170,6 +172,15 @@
     unwatchFn = undefined;
     unwatchPath = undefined;
   }
+
+  onDestroy(() => {
+    if (file) {
+      file.close();
+    }
+    if (unwatchFn) {
+      unwatchFn();
+    }
+  })
 </script>
 
 <div class="flex flex-col">

examples/api/src/views/FileSystem.svelte

@@ -35,7 +35,6 @@ tauri = { workspace = true }
 thiserror = { workspace = true }
 url = { workspace = true }
 anyhow = "1"
-uuid = { version = "1", features = ["v4"] }
 glob = { workspace = true }
 # TODO: Remove `serialization-compat-6` in v3
 notify = { version = "8", optional = true, features = [

plugins/fs/Cargo.toml

@@ -68,9 +68,9 @@ fn main() {
 Afterwards all the plugin's APIs are available through the JavaScript guest bindings:
 
 ```javascript
-import { metadata } from '@tauri-apps/plugin-fs'
+import { stat } from '@tauri-apps/plugin-fs'
 
-await metadata('/path/to/file')
+await stat('/path/to/file')
 ```
 
 ## Contributing

plugins/fs/README.md

@@ -101,6 +101,7 @@ const COMMANDS: &[(&str, &[&str])] = &[
     ("fstat", &[]),
     ("exists", &[]),
     ("watch", &[]),
+    // TODO: Remove this in v3
     ("unwatch", &[]),
     ("size", &[]),
 ];

plugins/fs/api-iife.js

@@ -1245,31 +1245,19 @@ type WatchEventKindRemove =
   | { kind: 'folder' }
   | { kind: 'other' }
 
+// TODO: Remove this in v3, return `Watcher` instead
 /**
  * @since 2.0.0
  */
 type UnwatchFn = () => void
 
-async function unwatch(rid: number): Promise<void> {
-  await invoke('plugin:fs|unwatch', { rid })
-}
+class Watcher extends Resource {}
 
-/**
- * Watch changes (after a delay) on files or directories.
- *
- * @since 2.0.0
- */
-async function watch(
+async function watchInternal(
   paths: string | string[] | URL | URL[],
   cb: (event: WatchEvent) => void,
-  options?: DebouncedWatchOptions
+  options: DebouncedWatchOptions
 ): Promise<UnwatchFn> {
-  const opts = {
-    recursive: false,
-    delayMs: 2000,
-    ...options
-  }
-
   const watchPaths = Array.isArray(paths) ? paths : [paths]
 
   for (const path of watchPaths) {
@@ -1283,15 +1271,35 @@ async function watch(
 
   const rid: number = await invoke('plugin:fs|watch', {
     paths: watchPaths.map((p) => (p instanceof URL ? p.toString() : p)),
-    options: opts,
+    options,
     onEvent
   })
 
+  const watcher = new Watcher(rid)
+
   return () => {
-    void unwatch(rid)
+    void watcher.close()
   }
 }
 
+// TODO: Return `Watcher` instead in v3
+/**
+ * Watch changes (after a delay) on files or directories.
+ *
+ * @since 2.0.0
+ */
+async function watch(
+  paths: string | string[] | URL | URL[],
+  cb: (event: WatchEvent) => void,
+  options?: DebouncedWatchOptions
+): Promise<UnwatchFn> {
+  return await watchInternal(paths, cb, {
+    delayMs: 2000,
+    ...options
+  })
+}
+
+// TODO: Return `Watcher` instead in v3
 /**
  * Watch changes on files or directories.
  *
@@ -1302,32 +1310,10 @@ async function watchImmediate(
   cb: (event: WatchEvent) => void,
   options?: WatchOptions
 ): Promise<UnwatchFn> {
-  const opts = {
-    recursive: false,
+  return await watchInternal(paths, cb, {
     ...options,
-    delayMs: null
-  }
-
-  const watchPaths = Array.isArray(paths) ? paths : [paths]
-
-  for (const path of watchPaths) {
-    if (path instanceof URL && path.protocol !== 'file:') {
-      throw new TypeError('Must be a file URL.')
-    }
-  }
-
-  const onEvent = new Channel<WatchEvent>()
-  onEvent.onmessage = cb
-
-  const rid: number = await invoke('plugin:fs|watch', {
-    paths: watchPaths.map((p) => (p instanceof URL ? p.toString() : p)),
-    options: opts,
-    onEvent
+    delayMs: undefined
   })
-
-  return () => {
-    void unwatch(rid)
-  }
 }
 
 /**

plugins/fs/build.rs

@@ -150,11 +150,6 @@ pub fn open<R: Runtime>(
     Ok(rid)
 }
 
-#[tauri::command]
-pub fn close<R: Runtime>(webview: Webview<R>, rid: ResourceId) -> CommandResult<()> {
-    webview.resources_table().close(rid).map_err(Into::into)
-}
-
 #[derive(Debug, Clone, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct CopyFileOptions {